Since the subject seems to have flared up again, I'm writing up my vision of the future of wikitext syntax. I think the desire of some here for double-spaced lists and the clarity of the spec can be reconciled by using a line-break syntax. I like the suggestion "\" (double backslash, in case your mailer screws that up).
So here's how it might work: within a line, "\" gets replaced by a BREAK element inline, so it can be used anywhere (inside headings, tables, etc.). When on a line all by itself, a BREAK element is added to the currently-open block-level element, which then remains open. Any totally blank line closes the element (as it does now).
So,
# first
# second
will produce
1. first
1. second
just as it does now. But
# first \ # second
will produce
1. first
2. second
or to be precise,
<ol><li>first <br> </li><li>second </li> </ol>
Likewise,
Blah blah
Blah blah...
is rendered as
<p>Blah blah</p> <p>Blah blah...</p>
but
Blah blah \ Blah blah...
becomes
<p>Blah blah <br> Blah blah...</p>
BTW, I did look at the links provided for other efforts at unifying syntaxes, but they both seemed to me to be too complex and too different from out current syntax to be practical here. I really think I can make a syntax that is dead simple, not a drastic change, and more powerful. I'll post the URL here when I finish the writeup.